CODEWITHSUNDEEP
pythonnumpyimport
Talia
Talia

Reputation: 3137

finding and replacing 'nan' with a number

I want to replace number 3 instead of all 'nan' in array. this is my code:

train= train.replace("nan",int(3))

But nothing changes in my array. Could u please guide me?

Upvotes: 12

Views: 29351

Answers (4)

Markus Kaukonen
Markus Kaukonen

Reputation: 414

The following works with floats, but could not quickly make it with integers... Terveisin Markus

import numpy as np
a=np.array([1,2,3,np.nan])
b=np.nan_to_num(a,nan=3)
print(f"a: {a}")
print(f"b: {b}")

a: [ 1. 2. 3. nan]

b: [1. 2. 3. 3.]

Upvotes: 0

SunRazor
SunRazor

Reputation: 1

This code changes all nan to 3:

y = np.nan_to_num(x) + np.isnan(x)*3

This code changes all 3 to nan:

y = x*(x!=3) + 0/(x!=3)

These methods only work with numpy arrays. Please note that np.nan_to_num(x) always changes nan to 0.

Upvotes: 0

Joe T. Boka
Joe T. Boka

Reputation: 6581

You can use np.isnan:

import numpy as np
train = np.array([2, 4, 4, 8, 32, np.NaN, 12, np.NaN]) 
train[np.isnan(train)]=3
train

Output:

array([  2.,   4.,   4.,   8.,  32.,   3.,  12.,   3.])

Upvotes: 33

Raymond Hettinger
Raymond Hettinger

Reputation: 226754

>>> import math
>>> train = [10, float('NaN'), 20, float('NaN'), 30]
>>> train = [3 if math.isnan(x) else x for x in train]
>>> train
[10, 3, 20, 3, 30]

Upvotes: 8

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